The invention relates to a method for phytosanitary treatment by foliar absorption, employing a combination between an active principle and a modified oil and a novel combination for employing said method.
The penetration of a phytosanitary active principle into a plant takes place either at leaf level, by foliar absorption, or at root level, by radicular absorption. The foliar absorption of an active principle is often difficult and very slow; this is especially the case for glyphosate which must be formulated with surface-active agents to increase this penetration. In the international patent application published under the number WO 99/03343, the inventors propose the use of methyl esters of ethoxylated fatty it, acids, in combination with vegetable oils, as well as wetting, dispersing and emulsifying agents, in herbicidal concentrations, to improve their stability. However, this approach is not suitable for water-soluble active materials because it leads to emulsions.
However, when small quantities of glyphosate are treated, that is to say of less than or equal to 306 grams per hectare, as is the case in the supervision of fallow land or for the treatment of young annual plants, none of the adjuvants currently employed with this active principle allow a rate of absorption of greater than 50% after 72 hours to be achieved. A period of rain following the treatment of a crop thus risks inducing pollution of the site, while a period of sunshine can cause the degradation of the active principle.
The applicants have thus endeavored to perfect a method of phytosanitary treatment by foliar absorption which allows a high absorption of a hydrophilic active principle by the plant in a short time, while limiting the harm to ecosystems, and using adjuvants which are much less irritant, especially for the eyes, than those used until today.
The invention relates to a method of phytosanitary treatment by foliar absorption, characterised in that it employs an aqueous composition comprising at least one water-soluble phytosanitary active principle and at least one modified oil, chosen from the ethoxylated oils having an ethylene oxide number, called EO index below, of greater than or equal to 20 and less than or equal to 60 and more particularly greater than or equal to 30 and less than or equal to 50 or from ethoxylated methyl, ethyl, linear or branched propyl or linear or branched butyl esters of oils, having an EO index of greater than or equal to 5 and less than or equal to 50 and more particularly greater than or equal to 6 and less than or equal to 20.
The modified oils used in the context of the present invention are of plant origin or of animal origin. Among the modified oils of animal origin which are employed in the method such as is defined above, is, for example, modified tallow oil. Among the modified oils of plant origin which are employed in the method such as defined above, are, for example, in the method sunflower, linseed, soybean, corn, peanut, copra, olive, palm, hydrogenated palm or rapeseed oils.
According to a particular variant of the method, such as defined above, the modified oil comprised in the composition employed is an ethoxylated methyl ester of an oil having an EO index of greater than or equal to 8 and less than or equal to 15.
According to another particular variant of the method, such as defined above, the modified oil comprised in the composition employed is an ethoxylated oil having an EO index of greater than or equal to 30 and less than or equal to 40.
The invention particularly relates to a method such as defined above, for which the modified oil comprised in the composition employed is modified rapeseed oil or modified sunflower oil.
By at least one modified oil, it is indicated that the composition employed in the method which is the subject of the present invention can comprise either a single modified oil, or a mixture of modified oils; in this latter case, it can be a mixture of modified oils of the same origin or a mixture of modified oils of different origins; it can also be a mixture of one or more ethoxylated oils such as are defined above with one or more ethoxylated esters of oils such as are defined above.
Phytosanitary treatment is understood in the context of the present invention as preferably meaning a fungicidal, insecticidal or herbicidal treatment and more particularly a treatment in which the active principle is a compound of chemical structure derived from the radical: xe2x80x94C(xe2x95x90O)xe2x80x94CH2xe2x80x94Nxe2x80x94CH2xe2x80x94P(xe2x95x90O).
An example of a compound of chemical structure derived from said radical is more particularly glyphosate or N-(phosphonomethyl) glycine, in the form of a water-soluble salt, such as, for example, the monoisopropylamine or trimethylsulfonium salts.
According to another aspect of the present invention, this relates to a composition comprising at least one water-soluble phytosanitary active principle, and at least one modified vegetable oil, characterized in that said modified vegetable oil is chosen from the ethoxylated oils having an ethylene oxide number of greater than or equal to 20 and less than or equal to 60 and more particularly greater than or equal to 30 and less than or equal to 50 or from the ethoxylated methyl, ethyl, linear or branched propyl or linear or branched butyl esters of oils, having an EO index of greater than or equal to 5 and less than or equal to 50 and more particularly greater than or equal to 6 and less than or equal to 20.
In order to improve its behavior in the cold, the alkoxylated oil can be prepared by incorporating, before its alkoxylation, from 1% to 10% by weight of glycerol. This problem is likewise resolved, by combining in the same composition, an alkoxylated vegetable oil such as defined above and an alkoxylated alkyl ester of a vegetable oil such as defined above, and more particularly an ethoxylated methyl, ethyl, linear or branched propyl or linear or branched butyl ester of a vegetable oil.
The invention relates more particularly to a composition, such as defined above, in which the active principle is a compound of chemical structure derived from the radical xe2x80x94C(xe2x95x90O)xe2x80x94CH2xe2x80x94Nxe2x80x94CH2xe2x80x94P(xe2x95x90O), and is very particularly glyphosate or N-phosphonomethylglycine, in the form of a water-soluble salt, such as, for example, the monoisopropylamine or trimethylsulfonium salts.
The invention relates very particularly to a composition such as defined above, in which the modified oil is an ethoxylated methyl ester of an oil having an EO index of greater than or equal to 8 and less than or equal to 15 and the phytosanitary active principle is glyphosate in the form of a water-soluble salt.
The invention also relates very particularly to a composition such as defined above, in which the modified oil is an ethoxylated oil having an EO index of greater than or equal to 30 and less than or equal to 40 and the phytosanitary active principle is glyphosate in the form of a water-soluble salt.
The invention finally relates very particularly to a composition such as defined above, in which the modified oil is modified rapeseed oil or modified sunflower oil.